title: A longitudinal study of indoor nitrogen dioxide levels and respiratory symptoms in inner-city children with asthma.
abstract: BACKGROUND
  The effect of indoor nitrogen dioxide concentrations on asthma morbidity among inner-city preschool children is uncertain.
  
  
  OBJECTIVE
  Our goal was to estimate the effect of indoor NO2 concentrations on asthma morbidity in an inner-city population while adjusting for other indoor pollutants.
  
  
  METHODS
  We recruited 150 children (2-6 years of age) with physician-diagnosed asthma from inner-city Baltimore, Maryland. Indoor air was monitored over a 72-hr period in the children's bedrooms at baseline and 3 and 6 months. At each visit, the child's caregiver completed a questionnaire assessing asthma symptoms over the previous 2 weeks and recent health care utilization.
  
  
  RESULTS
  Children were 58% male, 91% African American, and 42% from households with annual income < $25,000; 63% had persistent asthma symptoms. The mean (+/- SD) in-home NO2 concentration was 30.0 +/- 33.7 (range, 2.9-394.0) ppb. The presence of a gas stove and the use of a space heater or oven/stove for heat were independently associated with higher NO2 concentrations. Each 20-ppb increase in NO2 exposure was associated significantly with an increase in the number of days with limited speech [incidence rate ratio (IRR) = 1.15; 95% confidence interval (CI), 1.05-1.25], cough (IRR = 1.10; 95% CI, 1.02-1.18), and nocturnal symptoms (IRR = 1.09; 95% CI, 1.02-1.16), after adjustment for potential confounders. NO2 concentrations were not associated with increased health care utilization.
  
  
  CONCLUSIONS
  Higher indoor NO2 concentrations were associated with increased asthma symptoms in preschool inner-city children. Interventions aimed at lowering NO2 concentrations in inner-city homes may reduce asthma morbidity in this vulnerable population.
authors.affiliation: Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Hansel
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Breysse
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Matsui
authors.forename: Jean
authors.initials: J
authors.lastname: Curtin-Brosnan
authors.forename: D'Ann L
authors.initials: DL
authors.lastname: Williams
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Moore
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Cuhran
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Diette
mesh_terms: D016902:Air Pollution, Indoor; D001249:Asthma / Q000503:physiopathology*; D015142:Baltimore; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis*; D012129:Respiratory Function Tests; D014505:Urban Population
chemical_list: D009585:Nitrogen Dioxide